Nonauditory Functions in Low-performing Adult Cochlear Implant Users

Area of Science:

• Audiology
• Neuroscience
• Speech-Language Pathology

Background:

• Cochlear implantation (CI) offers substantial benefits but exhibits high variability in speech recognition outcomes.
• The reasons for this variability, especially in low-performing CI users, remain under-researched.
• Top-down cognitive and linguistic mechanisms are crucial for decoding speech signals in CI users with limited perceptual input.

Purpose of the Study:

• To investigate the neurocognitive and linguistic factors differentiating low-performing (LP) from high-performing (HP) cochlear implant (CI) users.
• To identify specific cognitive and linguistic skills that correlate with speech recognition variability in CI recipients.

Main Methods:

• Compared 15 low-performing (LP) and 19 high-performing (HP) post-lingual CI recipients using comprehensive neurocognitive and linguistic test batteries.
• Assessed functions including attention, memory, inhibition, working memory, lexical access, phonological input, and automatic naming.
• Utilized pairwise comparisons and discrimination analysis to differentiate between the LP and HP groups.

Main Results:

• Significant differences observed between LP and HP groups in phonological input lexicon and word retrieval (p=0.0039).
• HP users demonstrated faster lexical access (p=0.017) and better discrimination of real vs. non-existing words (p=0.0021).
• HP users outperformed LP users in neurocognitive subtests, notably attention (p=0.003). Linguistic performance was the primary discriminator, followed by cognitive functioning (r=0.68, p=0.0075).

Conclusions:

• Severe phonologically based deficits in rapid automatic speech processing are key differentiators between low and high-performing CI users.
• Cognitive functions, particularly attention, may play a partial role in mitigating speech processing difficulties for CI recipients.